1. to add the 1st segment -B+C, obvious and enough to draw an arc center on -B with radius 1, which intersects at the point +C the vertical to the half of A-B, as well as the arc from A radius phi at the point -D.
2. from -D clockwise to +E, and back to counterclockwise to -F, thanks to an arc from A, symmetrical to the previous on -B, radius = 1, intersecting in -F the arc from -B with radius -BA.
5. Need a fifth figure?
3. from -F clockwise to +G, then counterclockwise to -H,
4. it's easy now,
again to close a triangle (+G-H+I) and open another one (-H+I-J)